A TiAl intermetallic compound that contains titanium and aluminum is known. The TiAl intermetallic compound is applied to parts that are required to be high in heat resistance and light in weight. As the parts, parts for a flying vehicle and an aerospace engine are exemplified. When the TiAl intermetallic compound is mechanically worked, a crack and a break are easily generated therein. When the crack and break are generated in the part made of the TiAl intermetallic compound, a region where the crack and the break are generated is required to be built up. The part made of the TiAl intermetallic compound is typically brittle, and when a filler material made of the same material as the base material is used to perform an buildup welding operation, a residual stress generated in the buildup welding portion is high, and a ductility is low. Thus, the break is easily generated, and the repairing work is difficult. For this reason, a brazing work that uses the filler material made of material different from the TiAl intermetallic compound is applied to the buildup welding operation to the part made of the TiAl intermetallic compound. It is desired to adequately repair the brittle base material that is exemplified for the TiAl intermetallic compound.
Japanese Patent No. 3,741,547 discloses a brazing method of using a diffusion brazing work of a part made of titanium aluminide that can attain a sufficient quality standard which is especially required in an aircraft field. A brazing method includes (a) a step of preparing a homogeneous mixture of a powder A and a powder B, (b) a step of mixing an organic binder with the powder mixture obtained in the step (a) to prepare a paste, (c) a step of depositing the paste to cover a gap of the part, and (d) a step of heating an assembly obtained in the step (c) in a vacuum furnace at a temperature between 1000° C. and 1300° C. for several minutes to 6 hours. The powder A is made of a titanium alminide alloy corresponding to a weight ratio of 40 to 90% of the total amount of the homogenous mixture. The powder B is made of an alloy, which has a melting point lower than a melting start temperature of the powder A, and contains as a main component, titanium or copper that allows the powder A to be chemically moistened, and corresponds to a weight ratio of 10 to 60% of the total amount of the homogeneous mixture (here, the above weight ratio between the powder A and the powder B is determined on the basis of an operation parameter of a method, a temperature and a granularity of a powder).
JP H04-367382A discloses a bonding body of a high strength TiAl in which a bonding condition is relaxed so as to improve a bonding portion quality. The bonding body of the high strength TiAl contains two TiAl intermetallic compound layers that are substances intended to be bonded, and two diffusion layers and a metal Ti layer. The two diffusion layers include a Ti3Al intermetallic compound layer provided between the two TiAl intermetallic compound layers. The metal Ti layer serves as an insertion material provided between the two diffusion layers.